Microscopy is a widely used method of analysis. Especially in the “life sciences,” it is an indispensable tool for, for example, characterizing tissues and cells. The slide has become established as the “interface” between the medium to be examined and the components of a microscope to be imaged. The slide is a glass plate with dimensions of 26×76 mm (ISO 8255-2) and a thickness of 1 to 1.5 mm. For example, the objects are applied to the slide in a thin layer (tissue section, liquid film) and usually covered with a cover glass (frequently 18 mm×18 mm; 0.16 mm thick). The filtration technique is likewise a widely used laboratory technique, especially for separating solids of various sizes or liquids.
In the combination of microscopy and filtration technique, the filter residue is examined microscopically following the filtration process. For this purpose the filter medium, e.g., the filtration membrane, must be removed from the filtration device and placed on the slide. This process requires high experimental deftness, especially in the case of thin membranes (e.g., 10 μm thick, 25 mm diameter) and is very time-consuming. In order for this process to be used routinely and cost-effectively, for example in medical diagnostics, e.g., in the examination of tumor cells filtered from a blood sample, it would be necessary to develop a simple and cost-advantageous solution that can be performed even by untrained personnel. In particular, isolation of selected individual cells, such as circulating tumor cells (mCTCs), or cell clusters for subsequent molecular diagnostic examination will be of increasing significance in the future because of the scientific advances made in this area.